Thin film deposition apparatus and cleaning method for the thin film deposition apparatus

Abstract

This process removes reaction products of the metal material deposited on the inner surface of the processing container of a film deposition apparatus used to deposit a film made of a metal material onto a substrate. [Solution] A film deposition apparatus for forming a film of a metal material on a substrate comprises a processing container, a mounting table placed inside the processing container on which the substrate is placed, a film deposition gas supply unit facing the mounting table, an upper gas supply system that supplies gas to the inside of the processing container via the film deposition gas supply unit, and a lower gas supply system that supplies gas to the area below the mounting table inside the processing container. The upper gas supply system and the lower gas supply system alternately supply to the inside of the processing container a first gas that reacts with the reaction products of the metal material to transform them into a first compound, and a second gas that reacts with the first compound to transform it into a second compound that can be sublimated.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a film forming apparatus and a cleaning method for the film forming apparatus.

BACKGROUND ART

[0002] A single-wafer type film forming apparatus is known that performs film forming processing by placing wafers as substrates one by one on a mounting table inside a processing container (see, for example, Patent Document 1). The film forming apparatus of Patent Document 1 includes an elevating mechanism that moves the height position of the mounting table up and down, and the mounting table is connected to the elevating mechanism by an elevating shaft that protrudes to the outside of the processing container through a through hole provided in the processing container. Further, in order to maintain the airtightness of the processing container, an expandable and contractible bellows is arranged between the rim of the through hole and the elevating mechanism. The film forming apparatus of Patent Document 1 further includes a purge gas supply unit, and the purge gas supply unit supplies a purge gas, for example, nitrogen (N₂) gas, to the inside of the bellows. This suppresses the entry of the reaction gas into the interior of the bellows and inhibits the deposition of reaction products on the inner surface of the bellows.

[0003] Further, the film forming apparatus of Patent Document 1 includes a mechanism for supplying a cleaning gas, for example, chlorine trifluoride (ClF₃) gas, to the lower surface side of the mounting table, and supplies the cleaning gas from the lower surface side of the mounting table into the processing container.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0004]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] The technology according to the present disclosure removes reaction products of a metal material deposited on the inner surface of a processing container of a film forming apparatus that forms a film made of the metal material on a substrate.

MEANS FOR SOLVING THE PROBLEMS

[0006] One aspect of the technology relating to the present disclosure is a film deposition apparatus for forming a film of a metallic material on a substrate, comprising: a processing container; a mounting table disposed inside the processing container on which the substrate is placed; a film deposition gas supply unit facing the mounting table; an upper gas supply system for supplying gas into the processing container via the film deposition gas supply unit; and a lower gas supply system for supplying gas below the mounting table inside the processing container, wherein the upper gas supply system and the lower gas supply system alternately supply into the processing container a first gas that reacts with the reaction products of the metallic material to transform them into a first compound, and a second gas that reacts with the first compound to transform it into a sublimable second compound. [Effects of the Invention]

[0007] According to the technology disclosed herein, reaction products of a metal material deposited on the inner surface of the processing container of a film deposition apparatus used to deposit a film made of a metal material onto a substrate can be removed. [Brief explanation of the drawing]

[0008] [Figure 1] This graph shows the change in the thickness of the zirconium film on a test specimen when hydrogen fluoride gas and boron trichloride gas are repeatedly supplied alternately. [Figure 2] This figure shows the configuration of a plasma processing apparatus as a film deposition apparatus according to one embodiment of the technology described herein. [Figure 3] This flowchart shows the cleaning process of the film deposition apparatus according to this embodiment. [Figure 4] Figure 3 is a flowchart showing a modified version of the cleaning process. [Figure 5] This figure shows a modified configuration of the plasma processing apparatus shown in Figure 2. [Modes for carrying out the invention]

[0009] To lower the Schottky barrier (SBH) for N-type semiconductors, it is being considered to form wiring using metallic materials with conduction bands close in energy level to those of silicon (Si) and silicon-germanium (SiGe), such as zirconium (Zr). The zirconium film is formed on a wafer using plasma generated by the excitation and decomposition of vaporized zirconium chloride (ZrCl4) in a CVD (Chemical Vapor Deposition) apparatus.

[0010] By the way, when zirconium film formation is repeated in a CVD apparatus, zirconium oxide (ZrO) is deposited on the surface of the mounting stage and the inner surface of the walls of the processing vessel. x ) and zirconium nitride (ZrN x Zirconium reaction products such as ) accumulate. Therefore, it is necessary to periodically perform a cleaning process to remove the zirconium reaction products from the surface of the mounting platform and the inner surface of the walls of the processing container.

[0011] In this case, when chlorine trifluoride gas, which is commonly used as a cleaning gas, reacts with zirconium to produce zirconium fluoride (ZrF4). However, zirconium fluoride is a stable product that does not sublimate easily and remains on the surface of the mounting platform and the inner surface of the walls of the processing container.

[0012] In contrast, the technology described herein alternately supplies a first gas and a second gas, each having a different composition, into the processing container as cleaning gases. As a result, even if the reaction products of the metal material deposited on the surface of the mounting platform or the inner surface of the processing container walls are transformed into stable products by a reaction with one of the gases, these stable products can be further transformed into sublimable products by the other gas. Consequently, the reaction products of the metal material can be removed.

[0013] Hereinafter, an embodiment of the technology relating to this disclosure will be described with reference to the drawings. First, the applicant confirmed whether it is possible to remove zirconium reaction products from a substrate by alternately using a first gas and a second gas.

[0014] Specifically, test specimen 1 was prepared by forming a zirconium film on a silicon nitride (SiN) substrate and then subjecting the zirconium film to an oxidation treatment to convert a portion of the zirconium film into zirconium oxide. Similarly, test specimen 2 was prepared by forming a zirconium film on a substrate and then subjecting the zirconium film to a nitriding treatment to convert a portion of the zirconium film into zirconium nitride.

[0015] A test apparatus was prepared, comprising a processing container capable of reducing internal pressure and a mounting platform placed inside the processing container. Hydrogen fluoride (HF) gas as the first gas and boron trichloride (BCl3) gas as the second gas were supplied alternately. At this time, the temperature of the mounting platform was set to 350°C, and the internal pressure of the processing container was set to 7 Torr. The flow rate of the hydrogen fluoride gas was set to 200 sccm, and before being supplied to the processing container, the hydrogen fluoride gas was temporarily stored in a tank for 2 seconds, and then supplied from the tank to the processing container in one second. Furthermore, the flow rate of the boron trichloride gas was also set to 200 sccm, and before being supplied to the processing container, the boron trichloride gas was temporarily stored in a tank for 10 seconds, and then supplied from the tank to the processing container in one second. Argon (Ar) gas was continuously supplied to the inside of the processing container as a purge gas.

[0016] Furthermore, the applicant confirmed the change in the thickness of the zirconium film in test specimens 1 and 2 when hydrogen fluoride gas and boron trichloride gas were repeatedly supplied alternately in the test apparatus. Figure 1 is a graph showing the change in the thickness of the zirconium film in test specimens 1 and 2 when hydrogen fluoride gas and boron trichloride gas were repeatedly supplied alternately.

[0017] As shown in Figure 1, it was confirmed that for both test piece 1 and test piece 2, when the alternate supply of hydrogen fluoride gas and boron trichloride gas was repeated about 60 times, the thickness of the zirconium film became 0 nm, that is, the zirconium film was completely removed. That is, the present applicant has obtained the finding that zirconium reaction products such as zirconium oxide and zirconium nitride can be removed by repeating the alternate supply of hydrogen fluoride gas and boron trichloride gas. In addition, since the zirconium film that remains as zirconium except for a part that has deteriorated is completely removed, the present applicant has obtained the finding that simple substance zirconium can also be removed by repeating the alternate supply of hydrogen fluoride gas and boron trichloride gas. The technology according to the present disclosure is based on this finding.

[0018] Further, during the repeated alternate supply of hydrogen fluoride gas and boron trichloride gas, for example, zirconium dioxide (ZrO2) is considered to be transformed into sublimable boron trifluoride (BF3) or zirconium chloride at normal temperature and removed through the chemical reactions shown in the following formulas (1) and (2), or the chemical reactions shown in the following formulas (3) and (4).

[0019] ZrO2+ 4HF → ZrF4+ 2H2O↑ … (1) 3ZrF4+ 4BCl3→ 4BF3↑ + 3ZrCl4↑ … (2) 3ZrO2+ 4BCl3→ 2B2O3+ 3ZrCl4↑ … (3) B2O3+ 6HF → 2BF3+ 3H2O↑ … (4)

[0020] Furthermore, it is considered that zirconium nitride and simple substance zirconium are also transformed into boron trifluoride or zirconium chloride by reacting with hydrogen fluoride gas or boron trichloride gas during the repeated alternate supply of hydrogen fluoride gas and boron trichloride gas, and then removed. In this case, it is considered that nitrogen (N2) gas, hydrogen (H2) gas or hydrogen chloride (HCl) gas is generated instead of water (H2O).

[0021] Figure 2 shows the configuration of a plasma processing apparatus as a film deposition apparatus according to one embodiment of the technology described herein. The plasma processing apparatus 10 in Figure 2 is a film deposition apparatus for forming a zirconium film (a film of a metallic material) on a wafer W (substrate). The plasma processing apparatus 10 includes a substantially cylindrical chamber (processing container) 11 in which the wafer W (substrate) is housed under reduced pressure. A mounting table 12 on which the wafer W is placed is arranged inside the chamber 11. A shower head 13 (film deposition gas supply unit) is also arranged on the ceiling of the chamber 11 so as to face the mounting table 12. The mounting table 12 and the shower head 13 are made of a corrosion-resistant metal, such as nickel (Ni). A temperature control device, such as a heater (not shown), is embedded in the walls of the mounting table 12 and the chamber 11, and the heater adjusts the temperature of the walls of the mounting table 12 and the chamber 11.

[0022] A processing space U is formed between the mounting base 12 and the shower head 13, and in the processing space U, as will be described later, zirconium chloride plasma is generated from zirconium chloride gas, which is a film-forming gas. The chamber 11 has a mounting base housing section 11a that houses the mounting base 12, and a support shaft housing section 11b that protrudes downward from the mounting base housing section 11a and houses a support shaft 33 that supports the mounting base 12. The interior of the mounting base housing section 11a includes the processing space U and communicates with the interior of the support shaft housing section 11b.

[0023] The plasma processing apparatus 10 also includes an upper gas supply system 14 that supplies film-forming gas and cleaning gas into the chamber 11 via a shower head 13, and a lower gas supply system 15 that directly supplies cleaning gas into the chamber 11. The upper gas supply system 14 has piping 16, six gas supply sources 17-20, 44, and 45 connected to the piping 16, and six valves 21-24, 46, and 47 positioned between the piping 16 and each of the gas supply sources 17-20, 44, and 45. A flow control device (MFC) (not shown) that controls the flow rate of the gas supplied from the corresponding gas supply source is also placed between each of the gas supply sources 17-20, 44, and 45 and the piping 16. Gas supply source 17 supplies zirconium chloride gas, which is the film-forming gas. Gas supply source 18 supplies an inert gas, such as argon gas, which functions as a purge gas or diluent gas. Gas supply source 19 supplies hydrogen fluoride gas, which is the cleaning gas. Gas source 20 supplies boron trichloride gas, which is a cleaning gas. Gas source 44 supplies hydrogen gas, which is a reducing gas. Gas source 45 supplies ammonia (NH3) gas, which is a nitride gas.

[0024] The shower head 13 is roughly disc-shaped and has a gas diffusion chamber 25 formed inside, and a number of gas holes 26 that connect the gas diffusion chamber 25 and the processing space U. The shower head 13 faces the wafer W placed on the mounting base 12. Gas supply sources 17-20, 44, and 45 are connected to the shower head 13 via piping 16, and each gas supply source 17-20, 44, and 45 supplies various gases to the gas diffusion chamber 25 via piping 16. The various gases supplied to the gas diffusion chamber 25 are then supplied to the inside of the chamber 11 via the gas holes 26.

[0025] The shower head 13 may also be constructed from a porous material. In this case, various gases are supplied to the shower head 13 from the piping 16 of the lower gas supply system 15 without providing a gas diffusion chamber 25 or numerous gas holes 26 in the shower head 13. At this time, the supplied gases are delivered to the inside of the chamber 11 via the pores of the porous material.

[0026] In the upper gas supply system 14, the type of gas supplied to the chamber 11 is controlled by controlling the opening and closing of valves 21-24, 46, and 47. For example, when the plasma processing apparatus 10 performs a film deposition process, valves 21, 22, and 46 are opened, and valves 23, 24, and 47 are closed, supplying zirconium chloride gas, argon gas, and hydrogen gas to the chamber 11. Furthermore, when removing zirconium reaction products (metallic material reaction products) deposited on the surface of the mounting table 12 and the inner surface of the chamber 11 walls by the cleaning process shown in Figure 3, valve 21 is closed, and valves 22-24 are opened, supplying hydrogen fluoride gas, boron trichloride gas, and argon gas to the chamber 11. In addition, when removing by-products other than zirconium reaction products, valves 21-24 are closed, and valves 46 and 47 are opened, supplying hydrogen gas and ammonia gas to the chamber 11. The opening and closing of each valve 21-24, 46, and 47 is controlled by a control unit (not shown) provided in the plasma processing apparatus 10. The control unit consists of a computer having at least a CPU and memory, and the memory stores recipes (programs) for performing film deposition and cleaning processes.

[0027] The lower gas supply system 15 includes a pipe 27, two gas supply sources 28 and 29 connected to the pipe 27, and two valves 30 and 31 positioned between the pipe 27 and each gas supply source 28 and 29. Between each of the gas supply sources 28 and 29 and the pipe 27, there is an MFC (not shown) that controls the flow rate of the gas supplied from the corresponding gas supply source. Gas supply source 28 supplies hydrogen fluoride gas, which is a cleaning gas. Gas supply source 29 supplies boron trichloride gas, which is a cleaning gas. The lower gas supply system 15 also has a gas supply hole 32 that opens toward the inside of the support shaft housing portion 11b of the chamber 11.

[0028] In the lower gas supply system 15, the supply of cleaning gas to the inside of the chamber 11 is controlled by controlling the opening and closing of each valve 30, 31. The opening and closing of each valve 30, 31 is controlled by the control unit, similar to the valves 21-24, 46, 47. The lower gas supply system 15 may also have a gas supply source that supplies an inert gas, such as argon gas, which functions as a purge gas.

[0029] Furthermore, an exhaust system 34 is positioned below the chamber 11. The exhaust system 34 includes a pump for exhausting the inside of the chamber 11, such as a turbomolecular pump or a dry pump (not shown), and an exhaust valve for controlling the pressure inside the chamber 11, such as an APC (Auto Pressure Controller) valve (not shown). A gas exhaust hole 35 is provided in the support shaft housing 11b, and the exhaust system 34 communicates with the inside of the support shaft housing 11b of the chamber 11 via the gas exhaust hole 35. When generating plasma inside the chamber 11, the exhaust system 34 reduces the pressure inside the chamber 11 to, for example, several tens of mTorr.

[0030] The gas exhaust hole 35 is positioned so as not to face the gas supply hole 32. For example, the gas exhaust hole 35 is positioned above the gas supply hole 32. This prevents the cleaning gas supplied from the gas supply hole 32 from being discharged from the gas exhaust hole 35 before it can diffuse inside the support shaft housing 11b. As a result, the removal of zirconium reaction products by the cleaning gas is prevented from being suppressed. Furthermore, by positioning the gas supply hole 32 downwards, the cleaning gas can be more easily distributed throughout the entire interior of the mounting base housing 11a.

[0031] A high-frequency power supply 36 is connected to the shower head 13, and the shower head 13 functions as an electrode. In addition, a matching device (not shown), such as a POP (Plasma Optimizer), is connected to the mounting base 12.

[0032] When the plasma processing apparatus 10 performs a film deposition process, the high-frequency power supply 36 generates an electric field inside the chamber 11 by supplying, for example, 450 kHz high-frequency power (hereinafter simply referred to as "high-frequency power") for plasma generation to the showerhead 13. The matching unit maintains the electric field generated inside the chamber 11 by changing the potential of the mounting stage 12. The electric field generated inside the chamber 11 excites and decomposes the film deposition gases, zirconium chloride gas and hydrogen gas, supplied inside the chamber 11, generating zirconium chloride plasma and hydrogen radicals. The zirconium chloride plasma then reaches the surface of the wafer W, and the zirconium chloride plasma that reaches the surface of the wafer W is reduced by the hydrogen radicals, thereby forming a zirconium film.

[0033] When the plasma processing apparatus 10 performs a cleaning process, the upper gas supply system 14 indirectly supplies hydrogen fluoride gas, boron trichloride gas, and argon gas into the chamber 11 via the showerhead 13. The lower gas supply system 15 directly supplies hydrogen fluoride gas and boron trichloride gas into the chamber 11 through the gas supply holes 32. When the cleaning process is performed, the high-frequency power supply 36 does not supply high-frequency power to the showerhead 13. Therefore, the cleaning process is a non-plasma process that does not use plasma.

[0034] As described above, in the plasma processing apparatus 10, the mounting base 12 and the shower head 13 are made of corrosion-resistant nickel. In addition, the ring-shaped member 37 surrounding the shower head 13 is made of ceramic, for example, silicon dioxide (SiO2), and the support shaft 33 is made of nickel, nickel alloy (for example, Hastelloy), or aluminum oxide (Al2O3). Therefore, the mounting base 12, shower head 13, support shaft 33, and ring-shaped member 37 are not corroded by hydrogen fluoride gas or boron trichloride gas.

[0035] However, since the walls of the chamber 11, which are components exposed to the interior of the chamber 11, are made of aluminum (Al), they are susceptible to corrosion by hydrogen fluoride gas and boron trichloride gas. To address this, the plasma processing apparatus 10 forms a nickel coating film 38 (corrosion-resistant protective layer) on the surface of the aluminum components that are exposed to the interior of the chamber 11. This prevents the components exposed to the interior of the chamber 11 from corroding. The coating film 38 may be made of a nickel alloy rather than pure nickel.

[0036] Furthermore, when performing the cleaning process, the upper gas supply system 14 supplies cleaning gas to the inside of the chamber 11 via the shower head 13. As a result, the cleaning gas spreads evenly throughout the upper surface of the mounting table 12 and the inside of the mounting table housing 11a, and the zirconium reaction products are removed from the upper surface of the mounting table 12 and the inner surface of the mounting table housing 11a.

[0037] However, the flow rate of the cleaning gas supplied via the showerhead 13 becomes low. As a result, the cleaning gas may not reach the underside of the mounting base 12 or the inside of the support shaft housing 11b (below the mounting base), and there is a risk that the zirconium reaction products deposited on the underside of the mounting base 12, the inner surface of the support shaft housing 11b, and the surface of the support shaft 33 will not be removed.

[0038] In contrast, the lower gas supply system 15 supplies cleaning gas to the interior of the support shaft housing 11b of the chamber 11 via the gas supply hole 32. This allows the cleaning gas to reach the underside of the mounting table 12 and the interior of the support shaft housing 11b, thereby removing zirconium reaction products deposited on the underside of the mounting table 12, the inner surface of the support shaft housing 11b, and the surface of the support shaft 33. In particular, because the lower gas supply system 15 directly supplies cleaning gas to the interior of the support shaft housing 11b via the gas supply hole 32, the flow velocity of the supplied cleaning gas is high, and it reaches not only the interior of the support shaft housing 11b but also the interior of the mounting table housing 11a. As a result, zirconium reaction products can be removed from the entire interior of the chamber 11.

[0039] Furthermore, the control unit of the plasma processing apparatus 10 controls the flow rate of the gas supplied from the gas supply sources 19, 20, 28, and 29 by each MFC to adjust the ratio of the flow rates of the cleaning gas supplied from the upper gas supply system 14 and the lower gas supply system 15, respectively, so that the cleaning gas is evenly distributed throughout the chamber 11.

[0040] Figure 3 is a flowchart of the cleaning process (cleaning method) of the film deposition apparatus according to this embodiment. The cleaning process in Figure 3 is performed by the control unit of the plasma processing apparatus 10 to remove zirconium reaction products. Note that the zirconium reaction products removed by the cleaning process in Figure 3 include not only zirconium oxide and zirconium nitride, but also elemental zirconium.

[0041] In the cleaning process shown in Figure 3, based on the above findings, hydrogen fluoride gas and boron trichloride gas are repeatedly supplied alternately, although either hydrogen fluoride gas or boron trichloride gas may be supplied first. Furthermore, when performing the cleaning process shown in Figure 3, the temperature of the mounting stage 12 is set to a temperature between 100°C and 500°C, and the temperature of the walls of the chamber 11 is set to a temperature between 100°C and 200°C.

[0042] Figure 3(A) shows the case where hydrogen fluoride gas is supplied first. First, after the wafer W is removed from inside the chamber 11, the upper gas supply system 14 and the lower gas supply system 15 supply hydrogen fluoride gas (first gas) to the inside of the chamber 11 (step S31). At this time, some of the zirconium reaction products react with hydrogen fluoride to be transformed into zirconium fluoride (first compound), water, nitrogen gas, and hydrogen gas. The nitrogen gas and hydrogen gas immediately dissipate, and since the temperature of the mounting stage 12 and the walls of the chamber 11 is above 100°C, the water also immediately vaporizes and dissipates. On the other hand, since zirconium fluoride is a stable product, it remains on the surface of the mounting stage 12 and the inner surface of the walls of the chamber 11.

[0043] Next, the upper gas supply system 14 and the lower gas supply system 15 stop supplying hydrogen fluoride gas, and after a predetermined time has elapsed, they supply boron trichloride gas (second gas) into the chamber 11 (step S32). At this time, zirconium fluoride reacts with boron trichloride to transform into boron trifluoride (second compound) and zirconium chloride (second compound). Since boron trifluoride and zirconium chloride can sublimate at room temperature, they immediately vaporize and disperse.

[0044] Subsequently, it is determined whether the termination conditions for the cleaning process have been met (step S33). The termination conditions include, for example, whether the number of executions of steps S31 and S32 has reached a predetermined number. The predetermined number is determined by prior experiments, etc.

[0045] If the conditions for terminating the cleaning process are not met, the process returns to step S31. This causes steps S31 and S32 to be executed repeatedly. On the other hand, if the conditions for terminating the cleaning process are met, the cleaning process is terminated.

[0046] Furthermore, while steps S31 and S32 are repeatedly performed, the upper gas supply system 14 continues to supply argon gas to the inside of the chamber 11. The argon gas functions as a purge gas, expelling nitrogen gas, hydrogen gas, vaporized water, boron trifluoride and zirconium chloride, as well as unreacted hydrogen fluoride and boron trichloride gas from the inside of the chamber 11.

[0047] Figure 3(B) shows the case where boron trichloride gas is supplied first. First, after the wafer W is removed from inside the chamber 11, the upper gas supply system 14 and the lower gas supply system 15 supply boron trichloride gas (first gas) to the inside of the chamber 11 (step S34). At this time, some of the zirconium reaction products react with the boron trichloride gas and are transformed into boron oxide (B2O3) (first compound), boron nitride (BN) (first compound), zirconium chloride, water, hydrogen chloride gas, and nitrogen gas. Hydrogen chloride gas and nitrogen gas immediately dissipate, and zirconium chloride and water immediately vaporize and dissipate. On the other hand, since boron oxide and boron nitride are stable products, they remain on the surface of the mounting stage 12 and the inner surface of the chamber 11 wall.

[0048] Next, the upper gas supply system 14 and the lower gas supply system 15 stop supplying boron trichloride gas, and after a predetermined time has elapsed, hydrogen fluoride gas (second gas) is supplied to the inside of the chamber 11 (step S35). At this time, boron oxide reacts with hydrogen fluoride gas to be converted into boron trifluoride (second compound) and water, and boron nitride reacts with hydrogen fluoride gas to be converted into boron trifluoride (second compound), nitrogen gas, and hydrogen gas. The nitrogen gas and hydrogen gas immediately disperse, and the boron trifluoride and water also immediately vaporize and disperse.

[0049] Subsequently, it is determined whether the termination conditions for the cleaning process have been met (step S36). The termination conditions for step S36 are similar to those for step S33; for example, they may include whether the number of executions of steps S34 and S35 has reached a predetermined number. Here again, the predetermined number is determined by prior experiments, etc.

[0050] If the conditions for terminating the cleaning process are not met, the process returns to step S34. This causes steps S34 and S35 to be executed repeatedly. On the other hand, if the conditions for terminating the cleaning process are met, the cleaning process is terminated.

[0051] In the cleaning process shown in Figure 3(B), the upper gas supply system 14 continues to supply argon gas to the chamber 11 while steps S34 and S35 are repeatedly executed. The continuously supplied argon gas then discharges nitrogen gas, hydrogen gas, hydrogen chloride gas, vaporized water, boron trifluoride and zirconium chloride, as well as unreacted hydrogen fluoride gas and boron trichloride gas from the chamber 11.

[0052] According to this embodiment, hydrogen fluoride gas and boron trichloride gas are alternately supplied to the inside of the chamber 11 as cleaning gases. As a result, even if the zirconium reaction products deposited on the surface of the mounting stage 12 and the inner surface of the chamber 11 walls are transformed into stable products (zirconium fluoride, boron oxide, and boron nitride) by reacting with one of the cleaning gases, these stable products can be further transformed into sublimable products (boron trifluoride and zirconium chloride) by the other cleaning gas. Consequently, the zirconium reaction products deposited on the surface of the mounting stage 12 and the inner surface of the chamber 11 walls can be removed.

[0053] Furthermore, in this embodiment, hydrogen fluoride gas and boron trichloride gas are alternately supplied into the chamber 11, and unreacted hydrogen fluoride gas and boron trichloride gas are discharged from the chamber 11 by argon gas as a purge gas. Therefore, the reaction product of zirconium does not react with both hydrogen fluoride and boron trichloride simultaneously, and the unintended generation of difficult-to-remove by-products can be suppressed.

[0054] As described above, in this embodiment, hydrogen fluoride gas and boron trichloride gas are supplied separately. Therefore, if the diffusion modes of hydrogen fluoride gas and boron trichloride gas inside the chamber 11 are different, for example, zirconium fluoride produced by the reaction of zirconium reaction products with hydrogen fluoride gas may not come into contact with boron trichloride gas. In this case, as a result, zirconium fluoride may remain without being removed. Also, boron oxide and boron nitride produced by the reaction of zirconium reaction products with boron trichloride gas may not come into contact with hydrogen fluoride gas, and boron oxide and boron nitride may remain without being removed. In contrast, the upper gas supply system 14 supplies hydrogen fluoride gas and boron trichloride gas into the chamber 11 via the same showerhead 13, while the lower gas supply system 15 supplies hydrogen fluoride gas and boron trichloride gas into the chamber 11 from the same gas supply hole 32. This allows the diffusion patterns of hydrogen fluoride gas and boron trichloride gas within the chamber 11 to be aligned, enabling zirconium fluoride to come into contact with boron trichloride gas, and boron oxide and boron nitride to come into contact with hydrogen fluoride gas. As a result, it is possible to prevent zirconium fluoride, boron oxide, and boron nitride from remaining unremoved.

[0055] Furthermore, as described above, in this embodiment, hydrogen fluoride gas and boron trichloride gas are supplied into the chamber 11 from the same showerhead 13 and the same gas supply hole 32. In other words, since hydrogen fluoride gas and boron trichloride gas share the same supply port into the chamber 11, there is no need to provide separate supply ports for hydrogen fluoride gas and boron trichloride gas, thus preventing the plasma processing apparatus 10 from becoming unnecessarily complicated.

[0056] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications and changes are possible within the scope of its essence.

[0057] For example, in this embodiment, hydrogen fluoride gas and boron trichloride gas were supplied alternately, but hydrogen fluoride gas and boron trichloride gas may be supplied into the chamber 11 simultaneously. However, in this case, care must be taken to prevent the generation of zirconium reaction products and by-products that are difficult to remove due to the simultaneous reaction of hydrogen fluoride and boron trichloride. If by-products are generated, it is necessary to set the temperature of the mounting stage 12 and the walls of the chamber 11 to a higher level to promote the sublimation of such by-products.

[0058] Furthermore, in the plasma processing apparatus 10, as the alternating supply of hydrogen fluoride gas and boron trichloride gas is repeated, there is a risk that by-products different from the zirconium reaction products may accumulate on the surface of the mounting stage 12 and the inner surface of the chamber 11 walls. Therefore, in order to remove such by-products, ammonia gas or hydrogen gas may be supplied into the chamber 11 after the zirconium reaction products have been removed.

[0059] For example, as shown in Figure 4(A), steps S31 and S32 may be repeated, and then step S33 may be performed before supplying ammonia gas or hydrogen gas into the chamber 11 (step S41). Alternatively, as shown in Figure 4(B), steps S34 and S35 may be repeated, and then step S36 may be performed before supplying ammonia gas or hydrogen gas into the chamber 11 (step S42).

[0060] At this time, by-products are converted into ammonium chloride (NH4Cl) and hydrogen chloride and removed. Furthermore, even if hydrogen fluoride gas or boron trichloride gas remains inside the chamber 11, these gases are converted into ammonium chloride and hydrogen gas by ammonia gas and hydrogen gas. This prevents corrosion of the chamber 11 walls by residual hydrogen fluoride gas and boron trichloride gas. Additionally, the zirconium film formed on the wafer W can be stabilized by converting (nitriding) it with ammonia gas.

[0061] Furthermore, the supply of ammonia gas and hydrogen gas may be carried out not only after the alternating supply of hydrogen fluoride gas and boron trichloride gas has ended, but for example, between the supply of hydrogen fluoride gas and the supply of boron trichloride gas.

[0062] Furthermore, the flow velocity of the cleaning gas supplied from the lower gas supply system 15 into the chamber 11 may be increased. For example, a fill tank 39 for temporarily storing cleaning gas may be placed between each valve 30, 31 of the lower gas supply system 15 and the chamber 11, and a valve 40 may be placed between the fill tank 39 and the chamber 11 (Figure 5(A)).

[0063] In this case, even if valve 30 or valve 31 is opened, keeping valve 40 closed allows cleaning gas to be stored in the fill tank 39 at high pressure. Then, by opening valve 40, cleaning gas can be supplied to the inside of the chamber 11 at a high flow rate all at once. This ensures that the cleaning gas reaches the underside of the mounting base 12 and the inside of the support shaft housing 11b. Furthermore, because the cleaning gas can be quickly distributed inside the chamber 11, throughput can also be improved.

[0064] If a fill tank 39 is provided, for example, when supplying hydrogen fluoride gas into the chamber 11, the hydrogen fluoride gas is stored in the fill tank 39 for 1 second, and then the valve 40 is opened for 1 second to supply the hydrogen fluoride gas into the chamber 11. Alternatively, for example, when supplying boron trichloride gas into the chamber 11, the boron trichloride gas is stored in the fill tank 39 for 10 seconds, and then the valve 40 is opened for 1 second to supply the boron trichloride gas into the chamber 11.

[0065] Furthermore, in the lower gas supply system 15, fill tanks 41 and 42 corresponding to the gas supply sources 28 and 29 are arranged, and a valve 43 may be placed between the fill tanks 41 and 42 and the chamber 11 (Figure 5(B)). In this case, for example, when supplying hydrogen fluoride gas into the chamber 11, the hydrogen fluoride gas is stored in the fill tank 41 for 1 second with the valve 43 closed, and then the valve 43 is opened for 1 second to supply the hydrogen fluoride gas into the chamber 11. Also, for example, when supplying boron trichloride gas into the chamber 11, the boron trichloride gas is stored in the fill tank 42 for 10 seconds with the valve 43 closed, and then the valve 43 is opened for 1 second to supply the boron trichloride gas into the chamber 11.

[0066] In the embodiments described above, hydrogen fluoride gas and boron trichloride gas were used as cleaning gases. However, instead of hydrogen fluoride gas, a hydrogen-containing gas containing a halogen element other than chlorine, such as hydrogen bromide (HBr) gas or hydrogen iodide (HI) gas, may be used. Alternatively, other chlorine-containing gases may be used instead of boron trichloride gas.

[0067] Furthermore, although the cleaning process shown in Figure 3 was used to remove zirconium reaction products in a plasma processing apparatus 10 that forms a zirconium film, it can also be used to remove reaction products in plasma processing apparatuses that form other metal films. For example, the cleaning process shown in Figure 3 may be used to remove titanium reaction products in a plasma processing apparatus that forms a titanium (Ti) film. It may also be used to remove molybdenum reaction products in a plasma processing apparatus that forms a molybdenum (Mo) film. Moreover, it may be used to remove tungsten reaction products in a plasma processing apparatus that forms a tungsten (W) film. [Explanation of Symbols]

[0068] U processing space W wafer 10 Plasma Processing Equipment 11 Chambers 12 Mounting platform 13 Shower head 14 Upper gas supply system 15 Lower gas supply system

Claims

1. A film deposition apparatus for forming a film of a metallic material on a substrate, Processing container and A mounting platform is placed inside the processing container on which the substrate is placed, A film-forming gas supply unit facing the aforementioned mounting platform, An upper gas supply system that supplies gas to the inside of the processing container via the aforementioned film-forming gas supply unit, The processing container includes a lower gas supply system that supplies gas to the lower part of the stand described above, A film-forming apparatus comprising an upper gas supply system and a lower gas supply system that alternately supplies into the processing container a first gas that reacts with the reaction products of the metal material to transform them into a first compound, and a second gas that reacts with the first compound to transform it into a sublimable second compound.

2. The film deposition apparatus according to claim 1, wherein the first gas is a hydrogen-containing gas containing halogen elements other than chlorine, and the second gas is a chlorine-containing gas.

3. The film deposition apparatus according to claim 1, wherein the first gas is a chlorine-containing gas and the second gas is a hydrogen-containing gas containing halogen elements other than chlorine.

4. The film-forming apparatus according to claim 1, wherein a corrosion-resistant protective layer is formed on the surface of a member that constitutes the processing container or is placed inside the processing container, and which is made of a material that is corroded by the first gas or the second gas, on the side exposed to the inside of the processing container.

5. The film-forming apparatus according to claim 4, wherein the corrosion-resistant protective layer is composed of pure nickel or a nickel alloy.

6. The film deposition apparatus according to claim 1, wherein the film deposition gas supply unit consists of a shower head or a porous body.

7. The lower gas supply system has a gas supply hole that opens toward the inside of the processing container. The film-forming apparatus according to claim 1, wherein the first gas and the second gas are supplied to the inside of the processing container from the same gas supply hole.

8. The system further comprises an exhaust system that exhausts the inside of the processing container through a gas exhaust hole, The film deposition apparatus according to claim 7, wherein the gas exhaust hole is positioned above the gas supply hole.

9. The film deposition apparatus according to claim 1, wherein the lower gas supply system has at least one fill tank for temporarily storing the first gas or the second gas.

10. The film deposition apparatus according to claim 1, wherein the metal material is one of zirconium, titanium, molybdenum, and tungsten.

11. A cleaning method for a film-forming apparatus that forms a film of a metallic material on a substrate, comprising: a processing container; a mounting table disposed inside the processing container on which a substrate is placed; a film-forming gas supply unit facing the mounting table; an upper gas supply system that supplies gas to the inside of the processing container via the film-forming gas supply unit; and a lower gas supply system that supplies gas to the area below the mounting table inside the processing container, wherein a film of a metallic material is formed on the substrate, A cleaning method for a film-forming apparatus, comprising the step of alternately supplying to the inside of the processing container a first gas that reacts with the reaction product of the metal material to transform it into a first compound, and a second gas that reacts with the first compound to transform it into a sublimable second compound, via the upper gas supply system and the lower gas supply system.

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